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Thursday, 12 October 2017

Climate change: and rising sea levels

When it comes to rising sea levels, it's one of the "least controversial aspects of climate science":

Scientists often refrain from linking single weather events to climate change, saying only that they fit with what they expect to see more of because of climate change.

But as the Earth warms and scientist better understand climate change, weather extremes have been shown to have been made more likely due to greenhouse gas pollution. In Australia, the record hot winter just passed was made 60 times more likely by climate change. Researchers have also linked warming sea temperatures to the catastrophic rainfall and flooding that killed 35 people in Australia in 2011.

Sea level rise is one of the least controversial aspects of climate science. It is progressing at 3.4mm per year globally, according to the Australian government’s Ozcoasts website. Perhaps not enough to appear in photographs against other variables, such as daily tides, but over time scientists agree this will cause problems with coastal housing and infrastructure.

The entire ice mass is capable of raising sea levels by 24.3 feet, about three inches more than previously realized

Located on the west coast of Greenland, 250 km north of the Arctic Circle, Greenland's Ilulissat Icefjord is one of the fastest moving glaciers in the world and it annually calves more than 35 cubic kilometres of ice. Greg OlsenBy Chris Mooney

Greenland, the world’s largest island and home to its second largest ice sheet, is a land of ragged cliffs, breathtaking fjords and unimaginable amounts of water on either side of the freezing point. It has also, until now, been something of a mystery.

Greenland drew some pointed attention during the world wars and the Cold War, thanks to its strategic location. But it is only today, thanks to rapid climate change, that scientists are beginning to take the full measure of all the earth, rock and ice in a place that’s now raising seas by nearly a millimetre every single year.

Two new studies of Greenland, using sophisticated technologies and large scientific teams to pull together and process the data, have now gone further in taking the full measure of the island through that ever-so-basic scientific act: mapping.

The first, a comprehensive seabed mapping project, relying in part on new data from NASA’s OMG (“Oceans Melting Greenland”) mission, concludes that the Greenland ice sheet is far more exposed to the planet’s warming oceans than previously known — and has more ice to give up than, until now, has been recognized.A section of glacier (bottom) is seen along the Upper Baffin Bay coast above Greenland. Mario Tama / Getty Images

The massive study, published last month in Geophysical Research Letters, pulls together a large number of data records to provide a comprehensive map of the shape of the seabed around and lying beneath Greenland’s glaciers, based on state of the art soundings taken by ships and other data sources.

The research — which pulls together a body of evidence that has now been accumulating for a while — measures the depth and contours of the ocean floor both beneath liquid water in Greenland’s fjords and beneath ice in places where the ocean may someday flow. The work was led by Mathieu Morlighem of the University of California, Irvine, with no less than 31 other authors from institutions in the United States, Canada, Britain and across Europe.